Read Environment Variables with Groovy

Environment variables can be easily accessed with Groovy with getenv() method as shown below.


def env = System.getenv()
//Print all the environment variables.

env.each{
println it
}
// You can also access the specific variable, say 'username', as show below
String user= env['USERNAME']



Spring’s JDBC Template Set Up for a Grail Application

To take an advantage of the Spring JDBC Template for any Grail application, the first thing you need to do, is to define the DataSource bean in resources.groovy , Don’t forget to have the jdbc driver(.jar) corresponding to your backend database server under the lib folder of your grail application.

For example ,resources.groovy is shown as below,

import org.springframework.jdbc.core.JdbcTemplate
import org.apache.commons.dbcp.BasicDataSource




beans = {
myDataSource(BasicDataSource) {
driverClassName = "oracle.jdbc.OracleDriver"
url ="jdbc:oracle:thin:@ . . . . . “
username = "myUser"
password = "myPass"
}
jdbcTemplate(JdbcTemplate)
{
dataSource=myDataSource
}

}



If you have used MS SQL server as your back end database, the driver class name and the url format is as follow.

myDataSource(BasicDataSource) {
driverClassName = "com.microsoft.jdbc.sqlserver.SQLServerDriver"
url = "jdbc:microsoft:sqlserver://myDataBaseServerURL"
}

Similarly for MYSQL database server, the driver class name and the url format could be as follows :

dataSource {
driverClassName = "com.mysql.jdbc.Driver"
url = "jdbc:mysql:// myDataBaseServerURL "
username = "myUser"
password = "myPass"
}

Once its set up you can simply make a query as follows
myResult = jdbcTemplate.queryForList (myQuery)

where myQuery is the query that needs to be execute on the remoteDatabase.

Generate Random Alphanumeric Random String of N Characters with Groovy or Java

I was googling for a Alpha-numeric Random String generation. I come up with two solution. One option is to generate Random Alphanumeric Strings with RandomStringUtils available on Apache Common . The following section of code is borrowed from java2s.com


import org.apache.commons.lang.RandomStringUtils;
public class RandomStringUtilsTrial {
public static void main(String[] args) {

//Random 8 chars string where letters are enabled while numbers are not.
System.out.print("8 char string using letters but no numbers >>>");
System.out.println(RandomStringUtils.random(8, true, false));

}
}


Other Option can be using the Java Uitil class Random as shown below. You don’t have to worry about Apache Common API. The following code section (written for Groovy) generates 100 '32 characters' long Alphanumeric Random string.



private static String validChars ="ABCDEFGHIJKLMNOPQRSTUVWXYZ1234567890_"
private int IDlength=32
int maxIndex = validChars.length()
for(i in 0..99)
{ String resultID = ""
java.util.Random rnd = new java.util.Random(System.currentTimeMillis()*(new java.util.Random().nextInt()))
for ( i in 0..IDlength ) {
int rndPos = Math.abs(rnd.nextInt() % maxIndex);
resultID += validChars.charAt(rndPos)
number=resultID
}

println resultID
}



Good luck !

cURL , A command line tool with URL Support !

One of my co-worker introduced a tool named cURL to me today. It a quite handy command line tool for transferring files with URL Syntax supporting most of the interner protocols like FTP, FTPS, HTTP, HTTPS, SCP, SFTP, TFTP, TELNET, DICT, LDAP, LDAPS and FILE. curl supports SSL certificates, HTTP POST, HTTP PUT, proxy tunneling , HTTP form based upload, proxies, cookies, user+password authentication (Basic, Digest, NTLM, Negotiate, Kerberos and many more)

You can download cURL from http://curl.haxx.se/ . It’s a free and open software tools.

For example curl http://nepalnews.com : return a html version of your web page in your console window. Its detail tutorial and example can be found at http://curl.haxx.se/docs/httpscripting.html

I have use curl on the following
curl -X POST -H 'Content-type: text/xml' -d @ http://myserver.com/process.gsp < firstfocus.xml

Here I am sending an xml file, firstfocus.xml, to the server myserver.com . process.gsp do calls the controller which helps in the business logic at the back end and return the result on my console window. It’s a pretty good tool for testing and development environment.
Thanks to Joshua for letting me know about this tool and its usage.

Free Java Technology Cources!

Dear Readers,
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• Java Programming (with Passion!)
  
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How to read a Java Session Back bean of a JSF page from JSP pages

In this section I am describing about accessing a JSF back bean from a JSP page.
Lets us take an example of a java back bean ServerInfo for a JSF page

// File Name : ServerInfo.java
package thomson.com;
public class ServerInfo {
String server;
String environment;

public String getServer() {
return server;
}

public void setServer(String server) {
this.server = server;
}
}

Bean is defined on faces-config.xml as following

<navigation-rule>
<from-view-id>/index.jsp</from-view-id>
<navigation-case>
<to-view-id>/process.jsp</to-view-id>
</navigation-case>
</navigation-rule>
<managed-bean>
<managed-bean-name>ServerInfoBean</managed-bean-name>
<managed-bean-class>thomson.com.ServerInfo</managed-bean-class>
<managed-bean-scope>session</managed-bean-scope>
</managed-bean>

Now lets take an example of JSF page section that sets up the java bean ServerInfoBean from the input text of the form as shown below

//File name: index.jsp
<f:view>
<h:form id="serverForm">
<h:outputLabel for="serverName">
<h:outputText value="Enter the Server Name"/>
</h:outputLabel>
<h:inputText id="serverName" value="#{ServerInfoBean.server}" required="true"/>
<h:message for="serverName"/>
<br>
<h:outputLabel for="environment">
<h:outputText value="Select Environment"/>
</h:outputLabel>
</h:form>
</f:view>

Now in process.jsp the back bean can be accessed as shown below

File name : process.jsp
..
<%
ServerInfo mbean = (ServerInfo) request.getSession().getAttribute("ServerInfoBean");
String server = mbean.getServer();
Out.print(“server name read from the jsf back bean =” +server)

%>


Read custom created XML file from a Groovy/Java class in a J2EE Web Application

I have a following xml file that I created to store the application name and Application Owner email address

//File name: EmailInfo.xml

< emailInfo>
< application> < name> Saleways < /name> < email> david@david.com< /email> < /application>
< application> < name> Mercantile House< /name> < email> binod@hotmail.com< /email> < /application>
< application> < name> BishowShop< /name> < email> bishow@hotmail.com< /email> < /application>
< /emailInfo>


Now I have a J2EE application that contains a Groovy or a Java class that access the above XML file. The method to access above html file using Groovy is presented below. Note that the xml file resides on the same location where the class exists.


def appName=[]
def appEmail=[]
java.net.URL url= this.getClass().getClassLoader().getResource("EmailInfo.xml");
java.net.URI uri = new URI(url.toString())
File f=new File(uri)
def emailInfo = new XmlSlurper().parse(f) //Specific to groovy
emailInfo.application.name.each {appName += it} //specific to groovy
emailInfo.application.email.each {appEmail += it} // specific to groovy

You simply can modify the above code for java classes. The final result for the above code is that appName contains the list of the Name and appEmail contains the list of the Email address. You can put it into hash map as below.

def emailMap=[:] //define an empty map
for(i in 0 .. appName.size()-1)
emailMap.put(appName[i].toString(),appEmail[i].toString())

Now you simply can access the email address of a person as shown below

println emailMap[“Mercantile House”] //prints binod@hotmail.com


Welcome to my Technical Blog!

I create this blog so that i can share all the technical stuffs that i came across as a software engineer in J2EE Technologies. I will be glad to receive your feedback for every post and share your idea on the postings.
Welcome you all.
~Bishow